Hyundai Repair: Elantra P0507 Idle, intake manifold gasket, hyundai elantra

Question
Hyundai Elantra 2003, MT.  Failed Emissions "P0507 Idle Control system RPM Higher than Expected". I took it to Advanced Auto due to check engine light being on. Same results stating P0507 "Idle Control System, RPM High" No replacement parts at advanced. They said Dealer item? Help please....Steve

Answer
P0507 doesn't mean that a particular part is defective.  While it's probable that there's a defective part, the code doesn't identify which part that is.  What the code means is that the ECM (engine control module) was unable to lower the idle to the preferred level.

If your car is still within the warranty period (5 years/60k miles in the U.S.), you should take it to the dealer for warranty service and let them worry about it.

For the P0507 code to occur, it's very likely that excessive air is entering the engine.  This could occur for a few different reasons.  The ones I've seen are:
1.  Leaking PCV hose
2.  Leaking intake manifold gasket
3.  Defective idle actuator.